Ablation of myocardial tissue is well known as a treatment for cardiac arrhythmias. In radio-frequency (RF) ablation, for example a catheter is inserted into the heart and brought into contact with tissue at a target location. RF energy is then applied through electrodes on the catheter in order to create a lesion for the purpose of breaking arrhythmogenic current paths in the tissue.
Ablation has been accomplished primarily by means of focal ablation, that is, ablation by a tip electrode at a distal end of the catheter. Thus, for linear ablation along a line or curve, the tip electrode is repositioned repeatedly or dragged across the tissue along the line or curve during a prolonged ablation.
Also known are irrigated ablation tip and ring electrodes which are effective at reducing electrode temperature during ablation to minimize the formation of char and coagulum. However, fluid load on the patient is a concern, especially where multiple electrodes are being irrigated.
Current EP catheters utilize a single irrigation lumen to deliver irrigation to one or more irrigated electrodes. Pump units consisting of one pump head are therefore used. As catheters become more complex, the need for multiple irrigation lumens becomes more critical. Currently, irrigation delivery to a catheter with multiple irrigation lumens requires the use of multiple pump units.
Accordingly, there is a desire for a catheter adapted for both focal and linear ablation for accomplishing linear lesions without repositioning of the catheter. In particular, there is a desire for a catheter with tip and ring electrodes that can provide irrigation fluid to different electrodes at different flow rates without the need for multiple pumps.